How would I go about assigning each character in a string a value in python?-CodePudding

If I had this set of variables:

(a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p, q, r, s, t, u, v, w, x, y, z) = (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)

How would I go about assigning them to each character from this:

string = 'python'

To this:

(p, y, t, h, o, n) = (15, 24, 19, 7, 14, 13)

Thanks in Advance

CodePudding user response：

If you are trying to establish a mapping between two tuples from a mapping between two elements, you can try to use comprehensions and convert it to tuple, like this example:

# a mapping on elements, not necessarily lambda
f = lambda x: x*2
# a tuple that you want to map from
t1 = (1,2,3)
# comprehension ( a generator object )
t2 = (f(x) for x in t1)
# convert it into a tuple. Output: (2, 4, 6)
print(tuple(t2))

Converting a string to a tuple can be done in a similar manner:

s = "Hello"
t = (x for x in s)
print(tuple(t)) # output ('H', 'e', 'l', 'l', 'o')

CodePudding user response：

If the only logic to use is to assign numbers to each alphabet serially, then we can use a simply loop over letters in the string and get there index from a string which stores all the alphabets.

letters = "abcdefghijklmnopqrstuvwxyz"

string = "python"

print([x for x in string], [letters.index(i) for i in string ])

OUTPUT

['p', 'y', 't', 'h', 'o', 'n'] [15, 24, 19, 7, 14, 13]

CodePudding user response：

If I understand you correctly, you're looking for a way to create the mapping between each character to its corresponding index position. So here maybe what you're searching:

from string import *

>>> ascii_lowercase               # string constants from string module
'abcdefghijklmnopqrstuvwxyz'
>>> mapping = {ch: idx for idx, ch in enumerate(ascii_lowercase)} # dictionary comprehension here
>>> mapping
{'a': 0, 'b': 1, 'c': 2, 'd': 3, 'e': 4, 'f': 5, 'g': 6, 'h': 7, 'i': 8, 'j': 9, 'k': 10, 'l': 11, 'm': 12, 'n': 13, 'o': 14, 'p': 15, 'q': 16, 'r': 17, 's': 18, 't': 19, 'u': 20, 'v': 21, 'w': 22, 'x': 23, 'y': 24, 'z': 25}
>>> mapping.get('p')
15
>>> mapping.get('h')
7
>>> mapping.get('o')
14

Edit -

based on @triplee suggested, you can also do ord directly:

ord('p')    #  112 - 97 = 15
ord('a')    #  97 

# convert each character to it's index:
mapping = [ord(c)-97 for c in s]   # then you can do the rest of work...

CodePudding user response：

You could use the builtin ord function, and do the assignment using the locals function to update the current variable in use locally.

>>> string = 'python'
>>> toinclude = dict(zip(string,map(lambda x:ord(x)-97,string)))
>>> toinclude
{'p':15,'y':24,'t':19,'h':7,'o':14,'n':13}
>>> locals().update(toinclude)
>>> p
15

you could also use the string library

>>> from string import ascii_lowercase
>>> string = 'python'
>>> toinclude = dict(zip(string,map(ascii_lowercase.index,string.lower())))
>>> toinclude
{'p':15,'y':24,'t':19,'h':7,'o':14,'n':13}
>>> locals().update(toinclude)
>>> y
24

SIDENOTE: the first method is a little bit slower but doesn't rely on any library, to make work the second method without any library use this:

>>> ascii_lowercase = 'abcdefghijklmnopqrstuvwxyz'